Pre-printed books refer to articles such as scientific research papers and scientific reports that have not been published in official publications, but are voluntarily published at academic conferences or through the Internet for the purpose of communicating with peers.

Open access resources refer to academic literature, such as peer-reviewed scientific papers, research reports and dissertations.

Users can read, download, copy, spread, print and retrieve the full text of the works for free through the Internet. The only restriction on users is that users should ensure the integrity of the author's works and indicate the corresponding citation information.

OA resources are produced with the rise of OA movement in international academic circles, publishing circles and library and information circles, and use the Internet to freely spread and make free use of academic information and scientific research achievements.

Types of office automation resources:

There are four types of open access resources: open access journals, open access knowledge bases, electronic publications and open access search engines.

(1) Open Access Journal is a kind of online journal, and its papers have been peer-reviewed. Famous open access journals include DOAJ, Open J-Gate, BMC, PLoS, High WirePress, PMC, free full text, etc.

(2) Open Access Warehousing is a mode in which the author puts academic research results in a specific format on the document server for users to use for free.

(3) Electronic preprint refers to scientific research papers, scientific reports and other articles that have not been officially published, but are voluntarily published at academic conferences or through the Internet for the purpose of communicating with peers. For example, the e-print arXiv Library established by the National Laboratory of the United States, China Scientific Papers Online, China Preprint Service System, Foreign Preprint Portal (SINDAP), Miracle Library, etc.

(4) In order to solve the problem that OA journals and OA warehouses are scattered, open access search engines emerge one after another. There are mainly socolar, the world's largest one-stop service platform for OA resources developed by China Education Books Import and Export Corporation, and Scirus retrieval platform developed by Elsevier, a famous foreign publishing company.